When I first started reviewing industrial automation deliverables, I assumed the biggest name in PLCs was also the safest bet—period. Siemens has the market share, the ecosystem, the certifications. I thought that was enough. Then a Q1 2024 quality audit changed how I think about PLC security and supplier selection. Now I can't unsee the gap between market leadership and actual operational safety.
Here's what I've learned from reviewing 200+ unique items annually for our automation projects: comparing Siemens PLC market share against its security advisory track record isn't just academic. It's the difference between a system that runs and a system that survives.
The Comparison Framework: Market Share vs. Security Readiness
Let me be clear about what we're comparing. On one side: Siemens PLC market share percentages—the raw numbers that show why Siemens dominates industrial automation. On the other: siemens plc security advisory posture—how the company handles vulnerabilities in its S7-1200, S7-1500, and Logo! product lines.
Most engineers look at one side. They either care about market dominance ("everyone uses Siemens, so it must be safe") or they obsess over every security advisory ("I need to patch immediately"). I used to be in the first camp. The trigger event that changed my mind? A vendor failure in March 2023 where a client's unpatched S7-1200 went down during a production run. The fix cost us $22,000 in redo work and delayed their launch by three weeks.
Here's what we're comparing across three dimensions:
- Market dominance vs. vulnerability disclosure — Does market share correlate with security responsiveness?
- Ecosystem breadth vs. patching complexity — TIA Portal connects everything, but does that make it harder to secure?
- Certification claims vs. real-world attack surface — IEC 62443 sounds great, but what actually happens in production?
Dimension 1: Market Dominance vs. Vulnerability Disclosure
As of Q3 2024, Siemens holds roughly 30-35% of the global PLC market share, according to publicly available industry analyses. That's nearly double the next competitor. When you're specifying an S7-1500 for a $500,000 production line, that dominance feels reassuring. You're not going to get fired for choosing Siemens.
But here's where my initial assumption collided with reality. Siemens also publishes more security advisories per year than any other PLC vendor. In 2023 alone, the Siemens ProductCERT released advisories covering multiple S7-1200 and S7-1500 vulnerabilities—including ones that could allow remote code execution. I've seen estimates of around 30-40 advisories annually for Siemens.
Now, is that a bad thing? Actually, no—or rather, it's complicated. A higher advisory count doesn't mean Siemens is less secure. It means they're better at disclosing vulnerabilities. But the practical consequence? If you're not checking those advisories, you're running unpatched systems. I rejected a batch of integration work in early 2024 because the integrator hadn't applied a critical firmware update for the S7-1200. They claimed it was "within industry standard." We rejected the batch, and they redid it at their cost. Now every contract includes firmware version requirements.
Comparison conclusion: Siemens market leadership comes with a disclosure responsibility they actually fulfill. But that creates a maintenance burden most teams don't budget for. The market share advantage doesn't automatically translate to security safety.
Dimension 2: Ecosystem Breadth vs. Patching Complexity
Siemens' key advantage is the TIA Portal ecosystem. One engineering environment for S7-1200, S7-1500, drives, and HMIs. It's genuinely impressive. For our $18,000 integration project last year, TIA Portal cut engineering time by maybe 30% compared to using separate tools.
The downside? You can't just patch one component. When a siemens plc security advisory comes out for the S7-1500, it might require a firmware update that changes your entire TIA Portal version compatibility. I've seen projects grind to a halt because the latest security patch required a TIA Portal version that wasn't compatible with an older S7-1200 on the same network.
Compare that with a simpler setup—say, just running standalone S7-1200s with minimal networking. Fewer features, but fewer dependencies. The ecosystem advantage becomes a liability when you need to patch quickly.
Comparison conclusion: The TIA Portal ecosystem is a double-edged sword. It's a competitive advantage for new installations, but a security liability for legacy mixed-version environments. If you're running a network with S7-1200 and S7-1500 on different firmware levels, your patching complexity multiplies.
Dimension 3: Certification Claims vs. Real-World Attack Surface
Siemens markets its IEC 62443 certification heavily—and they should. It's the gold standard for industrial cybersecurity. In 2024, they achieved certification for multiple product lines. That's not nothing. It means Siemens has gone through rigorous third-party testing.
But I've learned not to confuse certification with invulnerability. In 2022—or rather, 2023, I think—there was a vulnerability in the S7-1500's communication protocol that required a specific configuration change. The product was certified. The protocol was still exploitable if configured incorrectly by the integrator.
I ran a blind internal audit last year: same PLC model, two different integrators. One configured the security settings correctly; the other left default passwords and open ports. The difference wasn't the product—it was the installation quality. Certification doesn't protect you from bad setup.
Comparison conclusion: IEC 62443 certification is meaningful, but it's a baseline, not a shield. The real security of your PLC depends more on your integration partner's quality control than on the product's certification. I've seen certified systems fail because the integrator skipped the security configuration steps.
What This Means for Your Next Siemens PLC Project
I'm not saying don't choose Siemens. That would be ridiculous. They're the market leader for good reasons: global support, comprehensive ecosystem, genuine security investment. But the comparison here reveals something most engineers miss.
The market share argument for safety is backward. Just because everyone uses Siemens doesn't mean your specific implementation is safe. The opposite might be true: the more widely deployed a platform is, the more attackers focus on it. And with the number of siemens plc security advisories increasing year over year (I'd say maybe 20-30% more in 2024 vs 2022, though I'd need to check exact counts), the maintenance burden is real.
Here's my practical advice, based on those 200+ reviews I mentioned:
- If you're a new installation: Siemens S7-1500 with TIA Portal is an excellent choice. You get the full ecosystem benefit with modern hardware. Budget for ongoing firmware updates—roughly 2-4 per year based on advisory cycles.
- If you're expanding an existing system: Prioritize security configuration over brand loyalty. A well-configured S7-1200 beats a poorly configured S7-1500 every time. Spend the money on integration quality control—I estimate it saves $5,000-$10,000 in potential rework per project.
- If you're concerned about patching complexity: Consider isolating older S7-300 or S7-1200 units on separate network segments. The 5 minutes of network segregation planning beats 5 days of emergency patching later.
The 12-point security checklist I created after that March 2023 failure has saved us an estimated $8,000 in potential rework across five projects. It includes specific items like: verify firmware version matches latest advisory, confirm TIA Portal compatibility before updating, and document default credential changes.
Market leadership without security discipline is just expensive shelfware. Siemens gives you the platform. You and your integrator provide the safety.